Circulator, bubbles or aquastat?

Gerry G

The circlator issue explains it. The aquastat is mounted directly off the output from the boiler and into the hot water supply. But I guess when the circ stops running, the hot water never leaves the boiler to activate the aquastat switch.

On my way to pick up a bronze circ, and will report the result.

Gerry G

Circulator, bubbles or aquastat? Plese help

I have a Carrier steam boiler to which I added a condensate heat system for a one room hot water zone. The hot water zone was run by an independent hot water boiler, which died last year. I followed Dan Hollohan's instructions on this site, and the system worked very well for about two weeks. In running the system, I made sure that the water temperature on the system didn't rise above 180.

Suddenly, on a cold day, the circulator pump (Taco 007-F4) seized up, and water would not circulate anymore through the hot water system. What was also odd, is that the steam boiler continued to run (since the hot water zone thermostat called for more heat) and the Honeywell aquastat L8148E did not shut the burner off. I had set the aquastat high limit at the lowest 150 temp. When the circ pump was working, the aquastat did shut the burner off.

In trying to diagnose the problem on this site, I initially thought that pump may be cavitating. But after taking the cartridge out, there were no visible damage marks on the impeller. However, the circulator was siezed up. After manually spinning the rotor and shaking the water out of the cartridge, the impeller spun freely.

I put the cartridge back in, re-adjusted the flow of the return lines, so that the temperature in the hot water zone did not go above 160 - the system would work for 2 days, and then seized up again. Again, the boiler continued to fire and the house temp rose to 80 (main thermostat set to 68).

I also have been diligent in trying to purge air from the hot water zone. It's a single room zone with Slant Fin baseboard that had no purge valve. I installed a valve (used a refrigerator tap valve on the 3/4 pipe) and when the system fired up, I opened the valve to purge the air out and waited until all air was out. I guessed that the system was air free when the vacuum created by the circulation started to suck air/water into the heating system. (Is this a wrong assumption?)

One guess is that the water was flashing as it was reaching the circulator. But the aquastat was set at the lowest settin, and I opened the return valve almost fully to drop the temp in the system.

Could it be as simple as a bad pump?

I have attached pics from the system.

Anthony Menafro

Aquastat

Make sure that your aquastat is close enough to the supply to properly sense the water temp.Is the aquastat on the supply side? also, I've found that water cooled pumps don't hold up to the high heat conditions and prefer to use oil cooled (100 series, etc.) pumps. The boiler continues to run after the pump stops pumping because the aquastat doesn't know the temp. of the water at the bioler, it only knows the temp. at the aquastat. I'd like to see the aquastat closer to the boiler. Good luck.

Anthony Menafro

[Deleted User]

Wet rotor circs and steam condensate systems don't mix....

I've always used a series 100 3 piece BRONZE circulator because I've seen every wet rotor pump in these applications die an early death due to oxide intrusion into the bearing assemblies regardless of make model and manufacturer. Locks 'em up every time.

The reason you akastat probably isn't shutting down is because your hydronic loop is seeing gravity circulation, and its not enough to wash enough water past the probe to shut down the burner.

Switch to a series 100 BRONZE circulator, and your circ problems will cease instead of seize.

As for purging, I typically purge mine with a power purge set up which requires you to isolate the hydronic loop from the steam boiler. Once purged, turn it back into the steam system and you have relatively air free operation. Tap saddle valves don't hold for crap.

Good Luck!

ME

J.C.A._3

Marks got it!

Never use anything but BRONZE circs for a condensate water system. Although I too don't like all the extra parts involved with the "3 piece" ones, they ARE a must.

The reason the house temp. goes up without the water system running is that it's still CALLING for heat, unless you pull the thermostat wires or disable the aquastat.
The boiler will continue to run because SOMETHING is telling it to, and will run off the pressuretrol until the water thermostat is satisfied.

B&G100 or Taco 110 bronze is your answer, disconnecting the thermostat until you do will keep your house from overheating. Chris

J.C.A._3

Gerry, Keep in mind....

Either one or the other call for heat from a thermostat will start and run the boiler. It doesn't care where the call is from, it's just there.

Until either is satisfied or the aquastat reaches it's temp.,from the water zone only call, the boiler will run.No flow past the aquastat will tell it to run.Maybe a shorter well insert will help.

Go forward and get thyself a bronze circulator. Hold onto your heart when thou doth see the price! Chris

Gerry G

Yeah, I just did a quick call around. Still beats a $3,500 install of a new boiler

Gerry G

One more q

Is it vital to get the 100 series of B&G or Tace, or will the bronze Taco 007 do? Local place that was open on a Sat. had the bronze 007, but not the 110.